1. Field of the Invention
This invention relates to conduit cleaners and, more particularly, to a nozzle assembly that controllably directs fluid from a pressurized supply to a fluid operated motor and exhausts the same therefrom.
2. Background Art
Fluid operated conduit cleaners are well known in the prior art. Compact, commercially available, fluid operated motors, that can be incorporated into these conduit cleaners, are presently commercially available. Known conduit cleaners incorporate these motors in much the same manner as is done in the structure in U.S. Pat. No. 3,740,785, to Latall.
More particularly, a nozzle/thruster section, defining a pressure chamber and a plurality of circumferentially spaced jet orifices in communication therewith, is attached at the trailing end of the motor. In one known construction, the motor is modified by welding a nipple to the trailing end thereof, which facilitates threaded connection of the nozzle section to the motor.
One particular problem with this construction is that, in addition to requiring multiple parts, a lengthy nozzle section is used which adds considerably and undesirably to the overall length of the conduit cleaner. This extended nozzle construction has the additional drawback that it, in conjunction with a multi-runner skid assembly, defines a captive space for foreign matter that may be encountered within a conduit, which foreign matter may inhibit or prohibit the withdrawal of the cleaner from a conduit. As can be seen in Latall, a substantial space exists. between the nozzle section and a surrounding skid assembly, which space is readily penetrable by roots and other foreign matter.
The interconnection of the pressure chamber on the nozzle and motor creates another problem in Latall. More specifically, the conduit which communicates between the pressure chamber and motor runs externally of the unit, which adds to the radial dimension thereof and introduces an additional structure which is prone to hangup in the conduit.
The nozzle section in Latall includes a plurality of circumferentially spaced jet orifices which direct fluid from the pressure chamber radially outwardly and in a trailing direction to produce a propulsion force and additionally scour the conduit within which the cleaner resides. The orifices are bored directly through the body of the nozzle section. This construction has several drawbacks.
First of all, each nozzle section has fixed flow characteristics by reason of the fixed diameter of the jet orifices. In the event that one wishes to alter the operating characteristics of the conduit cleaner, the nozzle must be disassembled and replaced with a fully assembled nozzle having jet orifices of a different size. As can be seen in Latall, a substantial amount of disassembly is required to remove the nozzle. Assembly of a replacement nozzle is equally complicated. The nozzle section also obstructs access to bolts used to maintain the nozzle section and motor in operative relationship.
In addition to the time consuming and complicated nature of this process, the user is required to keep on hand a suitable supply of nozzles to permit the desired reconfiguration of the conduit cleaner.
Because high pressure fluid is directed through the jet orifices, they are prone to wear. Designers must usually compromise between materials which wear well but whose cost makes it prohibitive to construct the complete nozzle therefrom, and a more affordable material that has less resistance to wear. Regardless of the material used, over time, the fluid will naturally enlarge the jet orifice size which alters the operating characteristics of the conduit cleaner. Once the size and shape of the jet orifices is appreciably altered, the entire nozzle section may be rendered useless. Since the nozzle section is relatively expensive and difficult to replace, the user may decide to use the defective unit at less than full efficiency rather than effecting the necessary repairs. Operation with a defective unit compromises the performance and reflects poorly on the manufacturer, even though the problem is attributable to normal wear.
Another problem with the conventional conduit cleaner is that it is difficult to effect lubrication thereof. Typically an outlet port on the unit has a fitting which defines a suitable opening to exhaust fluid. When it is desired to lubricate the unit, the user is required to remove this fitting and replace it with a grease fitting, as permits the introduction of lubrication through a conventional gun. Once the lubrication is completed, the grease fitting is removed and replaced with the fitting having the orifice. This operation is inconvenient and time consuming. Due to the inconvenience, there may be a tendency of the user to lubricate the unit less frequently than is necessary, which may shorten the life of the unit.